A manipulator, for example an industrial robot, has a stand which is rotatably arranged on a foot fixed to a base plate and which supports a first robot arm which is rotatable in relation to the stand. At the outer end of this arm, a second robot arm is rotatably journalled. This second arm is rotatable about its own longitudinal axis and supports, at its outer end, a robot hand which is provided with a tool attachment and which is rotatable in two degrees of freedom relative to the second arm. To achieve movement of the mentioned robot arms and the hand, a drive means is arranged at each axis. Each such drive means comprises a motor and a reduction gear with a high gear ratio.
An industrial robot of the above-mentioned kind has an operating range which is limited by the physical extent of the arms of the robot as well as the mobility around the axes. An industrial robot fixed to a base plate therefore has a given operating range within which the workpieces to be machined by the industrial robot must be introduced. However, an industrial robot may be used for a wide variety of tasks, and for this reason demands are sometimes made for a changed accessibility or a changed operating range. By moving the industrial robot to a new attachment point, the operating range may be moved, but in order to change the operating range, it is also required that the structure of the industrial robot be changed. This can be achieved by replacing parts of the robot, for example the stand or some of the robot arms.
From the publication "IRB 6400 Industrial Robot", ABB 6397 032-145, March 1994, an industrial robot is known in which the operating range can be increased by extending the second arm. This is achieved by providing the second arm with an extension module. The operating range can also be changed by so-called shelf mounting, in which case an angular module is joined to the stand. This module gives the robot a changed operating range allowing it to work in front of and under itself. One problem with the described methods of increasing the flexibility of the robot by reconstructing it is that a production loss arises during the mounting time. An additional problem is that the reconstruction entails new cabling, which results in additional costs. A robot configuration changed in this way also entails a reprogramming of the control equipment of the robot.